Overshot



Dec. 23, 194i. C, E LANG 2,266,873

OVERSHOT Filed Nov. 21, 1958 Patented Dec. 23, 1941 UNITED STATES"cargar oFFIcE' OVERSHOT Charles Eugene Lang, Houston, Tex.

Application November 21, 1938, Serial No. 241,510

3 Claims.

This invention relates to overshots and although not limited theretowill be found particularly useful in so called wire line core drills.

Conventional wire line core drilling equipment includes a drill stemhaving a drill bit on the lower end thereof, and a core barrel that isdropped into the drill stem to receive the core andv later removed withthe core therein by means of a wire line and an overshot. Such corebarrels usually have latching means to engage cooperating elements intheA drill stem, whereby the core barrel is held. in a position toreceive the core cut by the bit. Such latching means are usually adaptedto be released by an upward pull on an element thereof engaged by theovershot and commonly called a spear head. If the latching means doesnot release, anexcessive tension is placed on the wire line which attimes results in breakage thereof. The carriers of Center bits,

collapsible bits and the like utilize similar latchesr and wire linesare likewise broken in connection therewith.

This invention has for its specific object the provision of a new andimproved overshot embodying means whereby when an upward, pull isexerted on it by the wire line, at a time when the latch of the corebarrel, center bit carrier or collapsible bit is stuck, the overshotwill automatically jar the latching 'means to cause it to release thespear head, and if such jar is insufficient to cause the latching meansto so release the spear head and there exists a danger of the wire linebeing broken by excessive tension, the overshot will automaticallyrelease the spear head.

Other objects will hereinafter appear.

The preferred embodiment of the invention is illustrated in theaccompanying drawing where- 1n:

Fig. 1 is a side elevation of the overshot about to engage the spearhead.

Fig. 2 is a similar view of the overshot engaging the spear head.

Fig. 3 is a similar view of the overshot imparting a jar to the spearhead to release the latching means not shown.

Fig. 4 is a view similar to Fig. 3, the overshot having released thespear head.

Fig. 5 is a view showing the attachment of the wireline to the overshot.

In the drawing the numeral I indicates the overshot body and the numeral2 the pulling rod, the latter being connected by suitable elements 3 andl to the wire line 5 (Fig. 5). Carried by the rod 2 is a hammer 6tapered downwardly and having a rounded nose 6a. The purpose of therounded nose is to make it possible for the hammer to penetrate anydebris which may have settled within the body so that the pin 8 may beinserted. The upper end of the hammer 6 is adapted to strike the head Iof the body I when the frangible pin 8 is sheared by an excessive pullon the rod 2', to jar the overshotv to effect the release of thelatching elements of the device to be removed from the drill stem. Thebody I is provided with vent openings Ia and 'Ib at its upper and lowerends, respectively, to permit free flow of liquid from the space withinthe body ahead of the hammer 6 and into the space be-` hind the samewhen it is moved within the body and especially when it moves upwardlyafter the shearing of the pin 8. Connectedk to the body I is a plunger9, having a fork 9-A on its lower end in which are pivoted at II) thedogs II. Thev pivot I9 is vertically movable in oppositely disposedslots I2 in the prongs of the fork 9a of the plunger 9. The plunger 9 ismovable in the sleeve I3 when the frangible pin i4 is sheared by anexcessive pull on the plunger- 9. The` sleeve i. I3 is provided withoppositely disposed vertical slots I5 to permit the free movement of thedogs II on the pivot I0, the upper end walls of the slots I 5 serving,as will hereinafter appear, to en` gage the inclined surfaces of theupper ends I6. of the dogs to swing the dogs into their inoperativepositions. The numeral I'I indicates a compression spring bearingupwardly against the shoulder I8 of the plunger 9 and downwardly uponthe ring I9 of the sleeve I3 to urge said plunger 9- upwardly in thesleeve I3 in a manner to be described subsequently in connection` withFig. 4.

The element 9 has a downwardly facing shoul-s. der intermediate itsends, which prevents the sleeve I3 from moving upwardly thereon any fur-Y ther than shown in Fig. l. The sleeve I3 is normally held in theposition shown by means of the shear pin I4, but is constantly urgeddownward by the spring Il. The dogs II are pivoted to each other on apivot pin I0, the ends of which float in slots in the bifurcated lowerend of the element 9, so that these dogs II may move up or down withrespect to both the element 9 and the sleeve I3. When the device isengaged over the top of a spear head the dogs are naturally lifted andspread as shown in Fig. l, until they engage beneath the spear head,whereupon they drop down to the position shown in Fig. 2 and engage thespear head. An upward pull on rod 2 will rst sever the upper shear pin,permitting the rod 2 to move to the position shown in Fig. 3. This givesa jarring action, but if this jarring action is insuii'icient todislodge the Iarticle on which the spear head is mounted, further pullwill shear the pin I4, thus allowing the sleeve I3 to drop down. If thissleeve drops down, the pin I reaches the lower end of its slot in theelement 9 and the dropping of the sleeve with respect to the dogspermits the dogs to spread, releasing the spear head. The sleeve isprevented from -dropping off however, because it engages the shoulderadjacent the upper ends of the respective dogs and is suspended therebyas shown in Fig. 4.

Now, when the overshot is lowered into the drill stem, as shown in Fig.l, the spear head 20 of the core barrel, or the like (not shown), entersthe lower end of the sleeve I3 and moves between the dogs II; and thedogs II engage the spear head 20, as shown by Fig. 2.

When an upward pull is exerted on the wire line 5 and is transmitted.through the connecting elements 3 and 4 to the pulling rod 2, the forceis transmitted through the shear pin 8, body I, plunger 9, frangible pinI4, sleeve I3 and dogs II, to the spear head 2|) of the core barrel, orthe like. And if the core barrel or the like (not shown) is free to moveupwardly in the drill stem, the removal thereof is effected while theelements of the overshot remain in the relative positions illustrated byFig. 2.

If the latching means of the core barrel, or the like (not shown) do notreadily disengage, or if the core barrel is otherwise stuck in the drillstem, then if the pull on the pulling rod 2 is increased to apredetermined point, the frangible pin 8 is sheared and the pulling rod2 moves suddenly upwardly in the body I so that the hammer 6 strikes thehead 'l to jar the overshot and the core barrel, or the like, to releasethe latter. If the core barrel is released and the upward pull on thepulling rod 2 is continued, then the removal of the core barrel, or thelike, will be effected by the overshot with the parts in the positionillustrated by Fig. 3.

If the jar imparted to the core barrel, or the like, by the hammer 6, asabove set forth, does not release the core barrel from -the drill stem,and the upward pull on the pulling rod 2 is increased to a point where adanger of breaking the `wire line 5 is imminent, then the frangible pinI4 lwill be sheared and the plunger 9 will move upwardly in the sleeveI3 from the position shown by Fig. 3 to the position shown by Fig. 4.This movement will cause the upper end walls of the slots I5 to move theupper ends I6 of the dogs Il inwardly, whereby the lower ends of thedogs II will be moved outwardly to release the spear head 28. rIhespring I'I insures such movement and consequent release by constantlyexerting a pressure tending to move the plunger 9 upwardly in the sleeveI3. The core barrel, or the like, will then be left in the drill stemand the overshot, with the parts illustrated in the position shown byFig. 4, removed from the drill stem, breaking of the wire line 5 and thetrouble and expense incident to the removal of the equipment after suchbreakage being thereby prevented.

Various other advantages of this invention will be apparent to thoseskilled in the art.

I claim:

, 1. An overshot including a body; a pulling rod; a hammer carried bysaid rod; a frangible pin to normally prevent sliding of said. rod insaid body; said rod being slidable in said body to cause said hammer tojar said body when an excessive pull is exerted on said pulling means; asleeve; a plunger; dogs pivoted to said plunger; a spring yieldablyurging said plunger upwardly in said sleeve; a frangible pin to normallyhold said plunger against movement in said sleeve; said plunger beingmovable upwardly in said sleeve to move said d'ogs into their inactivepositions when a greater excessive pull is exerted on said rod.

2. A retrieving tool including gripping means, means movable to oneposition with respect to said gripping means to hold the gripping meansin gripping position, a pulling means, and means normally connectingsaid movable means to said pulling means, whereby said movable meanswill be caused to hold said gripping means in gripping position by apull on said pulling means, said connecting means being yieldable underan eX- cessive pull on said pulling means to allow said movable means tomove with respect to said pulling means and gripping means so as torelease said gripping means for movement to inactive position.

3. A retrieving tool including gripping dogs, a sleeve having adownwardly tapered inner surface movable upwardly with respect to saiddogs to engage said dogs and hold them in contracted gripping position,a pulling means, and means normally connecting said sleeve to saidpulling means whereby said vsleeve will be held upwardly to hold` saidgripping means in contracted gripping position by a pull on said pullingmeans, said connecting means being yieldable under an excessive pull onsaid pulling means to allow said sleeve to move downwardly with respectto said pulling means and said' gripping dogs thus permitting saidgripping dogs to expand to nongripping position.

CHARLES EUGENE LANG.,

